This invention relates to a panel type portable television receiver using a liquid crystal display panel with a dot matrix array.
Recently, the picture quality of a liquid crystal display device for a picture display of the dot matrix type has been markedly improved. With this improvement, development of the so-called liquid crystal television has approached a practical level.
The liquid crystal display is categorized into two types of display devices. One of the two is a liquid crystal display device using a dot matrix liquid display panel of the twist nematic type, which displays numerals and characters and is mainly used in desk-top calculators, and the like. The other is a liquid crystal display device using a liquid display panel of an active matrix type, in which a silicon substrate containing integrated switching MOS transistors is used as the substrate of the liquid display panel. The liquid crystal display panel of this type is further classified into a DSM type panel and a guest-host type panel.
When comparing the liquid crystal display panels of the twist nematic and active matrix types, the latter is superior to the former in term of the contrast present in a displayed picture. The active matrix type display panel, however, has the following disadvantages. Since the active matrix type display panel uses a silicon substrate, the display device based on such a panel must be limited in size and its manufacturing cost is high. Because of these disadvantages, the dot matrix liquid display panel of the twist nematic type, rather than the active matrix type display device, is suitable for use as the display device of a liquid crystal television receiver. When this dot matrix liquid display panel of the twist nematic type is used, a problem occurs in obtaining an adequate gradation display due to insufficient picture contrast under adverse lighting conditions.